Method for mounting a tyre on a rim or demounting a tyre from a rim and apparatus therefore

ABSTRACT

The present invention relates to a method and an apparatus for mounting a tyre on a rim or demounting a tyre from a rim. The method includes the steps of rotating the wheel (tyre/rim assembly) by an electric motor about an axis, checking the current consumption of the electric motor during the mounting and demounting operation, and continuously and automatically adjusting a specific combination of torque and speed of the electric motor during the mounting/demounting operation. The apparatus for mounting a tyre on a rim or demounting a tyre from a rim comprises an electric motor for rotating the wheel (rim/tyre assembly) about an axis, a sensing device for sensing the motor current and transmitting corresponding signals to a control device and an adjustment controller for continuously and automatically adjusting a specific combination of torque and speed of the electric motor during the mounting/demounting operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/698,042, filed Sep. 7, 2017, which is divisional of U.S. patentapplication Ser. No. 14/517,413, filed on Oct. 17, 2014, which is acontinuation-in-part of U.S. patent application Ser. No. 13/013,249,filed on Jan. 25, 2011, no U.S. Pat. No. 8,967,223, issued on Mar. 3,2015, which claims the benefit of European Patent Application No. 10 000720.2, filed on Jan. 25, 2010, the disclosures of which are herebyincorporated by reference herein in their entireties.

TECHNICAL FIELD

The invention concerns a method for mounting a tyre on a rim ordemounting a tyre from a rim. Furthermore, the invention concerns anapparatus for mounting a tyre on a rim or demounting a tyre from a rim.

BACKGROUND

An apparatus for mounting a tyre on a rim or demounting a tyre from arim with an electric motor which drives a shaft of a rotary disc isalready known from the prior art. For example EP O 911 190 disclosessuch an apparatus. Thereby, an electric motor is used which can bepowered with different supply voltages as the supply voltage differs fordifferent countries. An apparatus for mounting a tyre on a rim ordemounting a tyre from a rim is shown in DE 42 05 045; especially DE 4205 045 shows a rim or a tyre being positioned on the rotary disc. Bymeans of a tyre fitting or removal tool the tyre is mounted on the rimor demounted from the rim. The electric motor is activatable by a footpedal. By a corresponding more or less activation of the foot pedal anoperator is able to change the motor torque and thus the movement of therotary disc.

Such a known apparatus allows a mounting and demounting of tyres whichprevents the tyres from damage as the operator is able to change themotor torque and adapt it to different requirements, e.g. a high motortorque for tyres comprising a high stiffness.

It is an object of the present invention to provide a method and anapparatus for mounting or demounting a tyre with which a furtherimprovement of the mounting and demounting process is achievedpreventing the tyres from damage.

SUMMARY

According to the present invention, there is provided a method formounting a tyre on a rim or demounting a tyre from a rim, the methodcomprises the steps of rotating the wheel (tyre/rim assembly) by anelectric motor about an axis, checking the current consumption of theelectric motor during the mounting and demounting operation andcontinuously and automatically adjusting a specific combination oftorque and speed of the electric motor during the mounting/demountingoperation.

For adapting the mounting/demounting conditions to the kind of tyreand/or rim to be treated, according to an advantageous embodiment of theinventive method, different specific combinations of torque and speed ofthe electric motor are provided, which may be selected for controllingthe mounting/demounting operation

In a further advantageous step of the inventive method, the specificcombinations of torque and speed of the electric motor are selected byadjusting the frequency and/or the amplitude of the motor current and/orthe voltage.

In order to facilitate the adjustment of the method to the kind of tyreand/or rim, or in order to select a specifically optimized operationmode, predetermined values of the frequency and/or the amplitude of themotor current and/or the voltage are provided, which correspond tospecific combinations of torque and speed of the electric motor.

When selecting specific operation modes by adjusting specificcombinations of torque and speed of the electric motor, differenttargets may be achieved. One specific combination of torque and speed ofthe electric motor may be selected such that the electric motor runs ona maximum speed level. Another specific combination of torque and speedof the electric motor may be selected such that the electric motor runson a minimum speed level. Moreover, a specific combination of torque andspeed of the electric motor may be selected such that the electricenergy consumption of the electric motor is minimized. Furthermore, aspecific combination of torque and speed of the electric motor may beselected such that the noise emission of the electric motor isminimized.

It has to be understood that other targets as those mentioned above, maybe achieved by selecting other specific combinations of torque and speedof the electric motor.

According to the present invention, there is provided an apparatus formounting a tyre on a rim or demounting a tyre from a rim, the apparatuscomprises an electric motor for rotating the wheel (rim/tyre assembly)about an axis, a sensing device for sensing the motor current andtransmitting corresponding signals to a control device, and adjustmentcontroller for continuously and automatically adjusting a specificcombination of torque and speed of the electric motor during themounting/demounting operation.

Advantageously, in order to enable the selection of specificcombinations of torque and speed of the electric motor, the adjustmentcontroller is adapted to adjusting the frequency and/or the amplitude ofthe motor current and/or the voltage.

Further advantageously, the adjustment controller provides predeterminedvalues of the frequency and/or the amplitude of the motor current and/orthe voltage.

Moreover, in the inventive apparatus, dependent on the specificcombination of torque and speed of the electric motor to be selected,one of the predetermined values of the frequency and/or the amplitude ofthe motor current and/or the voltage may be set.

In one embodiment, the adjustment controller includes a pedal of thetyre mounting/demounting apparatus, whereby an operator may easilyselect a desired combination of torque and speed of the electric motor

Alternatively or additionally to the selection by a pedal, theadjustment controller is provided in the control unit of the tyremounting/demounting apparatus. The desired combination of torque andspeed of the electric motor may than be selected directly at the controlunit.

Further according to the present invention, in order to improveprecision of measurement and thus, to improve the inventive method,indirect measurement of the resistance torque through gauging thecurrent absorbed by the electric motor may be integrated, or a directmeasurement may be executed by providing the tyre mounting/demountingapparatus with a torque sensor of any known type. Alternatively oradditionally, torque may be calculated starting from a speedmeasurement, e.g. by a rotary encoder. Further alternatively, a straingauge is provided, which may be mounted on the tool support arm or inany other suitable position within the tyre mounting/demountingapparatus.

It has to be understood that all these different methods to assess theactual mounting/demounting conditions could be used as alternatives orin combination.

Moreover, there is disclosed a method for mounting a tyre on a rim ordemounting a tyre from a rim, wherein the wheel (tyre/rim assembly) isrotated by an electric motor about an axis, wherein the motor currentfed to the electric motor is controlled dependent on the rotationalspeed and torque required for the mounting and/or demounting operation,and wherein the motor current is automatically changed to apply a hightorque peak, when the measured motor current is greater than a presetlimit at a low rotational speed during a preset time. It is autonomouslydetected when a high torque peak is required and such a high torque peakis automatically applied. The high torque peak is achieved in changingthe motor current, in particular in changing the frequency and/or theamplitude of the motor current. The applied high torque peak is alsocalled “boost” function in the following. The “boost” function issynonymous with an activation of a pedal with which the electric motoris started. That means the “boost” function simulates a pedal retry ofan operator in increasing the motor current fed to the electric motor.Such a motor current changing is useful as speed and torque requirementsduring mounting and/or demounting operations are different depending onthe kind of the mounted and/or demounted tyre. In particular, the sidewalls of the tyres have different stiffness. For tyres with a highstiffness, e.g. run flat tyres, low speed and high torque are required,however for basic operations high speed and low torque are required.Advantageously, the method according to the invention prevents the tyresfrom damage during mounting and/or demounting process. The high torquepeak is applied to the electric motor when the present current isgreater than a preset limit at a low rotational speed during a presettime. The actual low speed corresponds e.g. to the nominal speed of themotor at 50 Hz (which approximately corresponds to 1500 rpm for astandard four-pole motor). The speed of the motor is reduced by means ofa gearbox to about 7 rpm at the main shaft. That means when the shaftrotated by the electric motor is slowed down due to a high request oftorque at a low rotational speed and this high request of torque existsduring a preset time, the motor current is changed.

Preferably, the preset time is longer than the period during which thehigh torque peak is applied.

In particular, the preset time is three to ten times longer than theperiod of applying the torque peak.

The motor current is preferably set back to normal condition afterapplying the torque peak. After applying the torque peak, the method formounting or demounting a tyre is continued with the motor current fornormal conditions until a further high request of torque is detected bythe converter. For example, the actual low speed corresponds to thenominal speed of the motor at 50 Hz—which approximately corresponds to1500 rpm for a standard four-pole motor—and the actual high speedcorresponds to the nominal speed of the motor at 100 Hz—whichapproximately corresponds to 3000 rpm for a standard four-pole motor.The actual low speed of the motor is reduced by means of a gearbox toabout 7 rpm at the main shaft, and the actual high speed of the motor isreduced by means of a gearbox to about 14 rpm at the main shaft.

Preferably, the frequency and/or the amplitude of the motor current isincreased within a preset maximum limit to apply a torque peak. Such apreset limit is given, e.g. stored, and prevents that the electric motoris driven with an excessive current frequency which leads to a damage ofthe electric motor.

The cycle of applying the torque peak and setting back to normalcondition can be repeated.

Furthermore, there is disclosed an apparatus for mounting a tyre on arim or demounting a tyre from a rim comprising an electric motor forrotating the wheel (rim/tyre assembly) about an axis, a controlleddevice for delivering the motor current to the electric motor and asensing device for sensing the motor current and transmittingcorresponding signals to a control device controlling the motor currentdependent on the rotational speed and torque requirement for themounting and/or demounting operation, wherein the control device is ableto change the motor current to apply a high torque peak, when themeasured motor current is greater than a preset limit at a lowrotational speed during a preset time. With respect to the advantages itis referred to the above mentioned explanations.

Preferably, a time counter is connected to the control device topredetermine a time limit interval during which a motor current greaterthan a preset limit is measured. Thereby, the time counter can be aseparate part or the time counter can be integrated into the controldevice.

The control device can comprise a microprocessor which adjusts a powerdriving circuit with power switches to control the motor current.

The electro motor is a two-phase or a three-phase electric motor, i.e.the electric motor is driven with two-phase current or three-phasecurrent.

Preferably, the apparatus comprises a low voltage circuit providing thecontrol device with low voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail herein after by meansof embodiments by way of example with reference to the Figures in which:

FIG. 1 schematically shows an apparatus in which a method according tothe invention can be conducted,

FIG. 2 shows a flow chart of the method according to the invention, and

FIG. 3 is a chart of characteristic curves of a specific electric motor.

DETAILED DESCRIPTION

In FIG. 1 a tyre changer is diagrammatically shown, the tyre changer 10comprising an electric motor 12, in particular three-phase motor, fordriving a drive shaft 14 of a rotary disc 16. Alternatively, a one-phasemotor or a two-phase motor, especially induction motor, can be used. Inparticular a four-pole motor is used. On the rotary disc 16 tyres beingcentered to the rotary axis A of the rotary disc 16 can be positioned. Atyre fitting or removal head 18 is fixed on a pivotable arm 20, the arm20 being attached to a housing 22.

The motor current, especially the frequency and/or the amplitude of themotor current fed to the electric motor 12 is changeable which resultsin a different speed of the driven shaft 14. Additionally, also thevoltage at electric motor 12 is changeable which also results in adifferent speed of the driven shaft 14. In order to detect the motorcurrent fed to the electric motor 12, a sensing device 24 is connectedwith the electric motor 12. Furthermore, the sensing device 24 isconnected with a control device 26. Signals from the sensing device 24are transmitted to the control device 26, for checking the currentconsumption of electric motor 12. Depending on the signals detected fromthe sensing device 24, the control device 26 is able to control themotor current dependent on the rotational speed and torque requirementfor the mounting and/or demounting operation. In particular, the controldevice 26 is able to change the frequency and/or the amplitude of themotor current and/or the voltage fed to the electric motor 12. Such achanging in the motor current is useful as speed and torque requirementsduring mounting and/or demounting operations are different depending onthe kind of the mounted and/or demounted tyre. In particular, the sidewalls of the tyres have different stiffness. For tyres with a highstiffness, e.g. run flat tyres, low speed and high torque are required,however for basic operations high speed and low torque are required.

The control device 26 is able to autonomously detect, when the rotationof the shaft 14 is slowed down due to high request of torque, and isable to automatically start a so-called “boost” function. This “boost”function is synonymous with an activation of a pedal with which theelectric motor 12 is started. That means the “boost” function simulatesa pedal retry of an operator. This provides a torque peak of theelectric motor 12. Thereby the current fed to the electric motor 12 ischanged in increasing the motor current fed to the electric motor 12within given limit values. The control device 26 autonomously detects arequirement of changing the motor current fed to the electric motor 12to apply a high torque peak. After detecting the requirement, the motorcurrent is automatically changed. An action of an operator is therebynot necessary. The control device 26 comprises a microprocessor 28, aninterface circuit 30 and a controlled device 32. The sensing device 24is connected with the microprocessor 28, signals from the sensing device24 indicating the motor current fed to the electric motor 12 beingtransmitted from the sensing device 24 to the microprocessor 28.Depending on these signals, the microprocessor 28 being able to adjustthe controlled device 32 comprising power switches to control the motorcurrent. The interface circuit 30 positioned between the microprocessor28 and the controlled device 32 serves for converting and forwarding thecommands of the microprocessor 28 to the controlled device 32. Theinterface circuit 30 provides voltage interface conversions, suppliesdead time protection and shut down function protection. The controlleddevice 32 comprising power switches which are used to drive the electricmotor 12 are positioned between the motor current sensing device 24 anda high voltage circuit 34, the high voltage circuit 34 powers theelectric motor 12.

Furthermore, a low voltage circuit 36 is provided comprising atransformer to reduce the voltage, a bridge rectifier, filter and aregulator to provide low voltage levels being provided to the interfacecircuit 30 and to the circuit of the microprocessor 28.

Furthermore, a time counter 37 is provided, the time counter 37 beingconnected to the control device 26, especially the microprocessor 28, topredetermine a time limit interval during which a motor current which isgreater than a preset limit is measured. When the measured motor currentis greater than a preset limit during the preset time, a high torquepeak is applied. Alternatively, the time counter 37 can be integratedinto the control device (not shown).

Alternatively to the “boost” function, specific combinations of torqueand speed of the electric motor during the mounting/demounting operationmay continuously and automatically be adjusted by control device 26.

The specific characteristic curves of an electric motor are known. FIG.3 shows such characteristic curves. As it can be seen from FIG. 3,dependent on the frequency of the current fed to the electric motor, andthe rotational speed of the motor, torque increases with the increase ofthe rotational speed up to a maximum torque, and by further increasingthe rotational speed, torque decreases.

Furthermore, by changing the amplitude of the current fed to theelectric motor, or by changing the voltage, the rotational speed of anelectric motor may be changed, which results in a torque value accordingto the specific characteristic curve of the electric motor.

By selecting the frequency and/or the amplitude of the motor currentand/or the voltage fed to the electric motor 12, a desired combinationof torque and speed of the electric motor may be adjusted. Furthermore,by continuously monitoring the selected frequency and/or the amplitudeof the motor current and/or the voltage fed to electric motor 12, thedesired combination of torque and speed of the electric motor may bemaintained constant during the mounting/demounting operation.

Alternatively, the desired combination of torque and speed of theelectric motor may be selected such that said combination varies duringthe mounting/demounting operation, e.g. for starting the mountingoperation at a low speed level, increasing the speed during the mountingoperation, and, lowering the speed for finishing the mounting operation.The respective selected speed of electric motor 12 results in acorresponding torque value according to the characteristic curve ofelectric motor 12.

For varying the speed of electric motor 12 during themounting/demounting operation, the selected frequency and/or theamplitude of the motor current and/or the voltage fed to the electricmotor 12 are not only continuously monitored, but also continuously andautomatically adjusted, e.g. according to the selected speed profile.

The frequency and/or the amplitude of the motor current and/or thevoltage fed to the electric motor 12 may also be selected for adjustinga desired torque value, e.g. depending on the kind of tyre to be mountedor demounted, or the specific mounting or demounting step. Exemplarily,when starting a demounting operation, the tyre bead has to be removedfrom the rim, by being pulled over the rim edge. Thereby, an increasedtorque value may be required, whereas torque may be lowered after afirst portion of the tyre bead has been lifted over the rim edge.Further exemplarily, different kinds of tyres may have side walls ortyre beads of different stiffness requiring different torque valuesduring identical mounting/demounting operation periods.

Thus, by selecting the frequency and/or the amplitude of the motorcurrent and/or the voltage fed to electric motor 12, torque and speedmay be constantly fine-tuned and adjusted depending on the actualoperating mounting/demounting conditions.

For executing the inventive method, control device 26 may be providedwith preselected values of frequencies and/or amplitudes of the motorcurrent and/or the voltages to be fed to electric motor 12, which leadto specific combination of torque and speed of electric motor 12, andwhich may be selected by the operator dependent on the kind of tyre tobe treated.

When selecting specific operation modes by adjusting specificcombinations of torque and speed of the electric motor, differenttargets may be achieved. One specific combination of torque and speed ofthe electric motor may be selected such that the electric motor runs ona maximum speed level. Another specific combination of torque and speedof the electric motor may be selected such that the electric motor runson a minimum speed level. Moreover, a specific combination of torque andspeed of the electric motor may be selected such that the electricenergy consumption of the electric motor is minimized. Furthermore, aspecific combination of torque and speed of the electric motor may beselected such that the noise emission of the electric motor isminimized.

For selecting a specific operation mode, dependent on the target to beachieved and/or the kind of tyre to be treated, the operator may usecontrol device 26, in which a variety of combinations of torque andspeed of electric motor 12 are stored. Alternatively or additionallythereto, the pedal by which electric motor 12 may be started, caninclude the additional functionality of selecting said specificoperation modes. The pedal may be coupled to control device 26, and, byactivating the pedal in a required manner, a respective operation modeis selected. The pedal may have different positions corresponding to thedifferent operation modes selectable by the pedal, or the pedal may bedesigned such that different operation modes may be selected by pushingthe pedal one time for generally starting the mounting/demountingapparatus, and several times thereafter, for selecting a desiredoperation mode. Naturally, other activation procedures are possible forselecting a desired operation mode.

In order to improve precision of measurement of the torque applied byelectric motor 12, indirect measurement of the resistance torque throughgauging the current absorbed by electric motor 12 may be integrated, ora direct measurement may be executed by providing the tyremounting/demounting apparatus with a torque sensor of any known type.Alternatively or additionally, torque may be calculated starting from aspeed measurement, e.g. by a rotary encoder. Further alternatively, astrain gauge is provided, which may be mounted on the tool support armor in any other suitable position within the tyre mounting/demountingapparatus.

A flow chart of the method according to the method including the “boost”function which is conducted with the apparatus as explained above isshown in FIG. 2.

In a first step, which is indicated with reference numeral 38, it isinspected if the foot pedal (not shown) is activated.

Only if the pedal is activated, that means if the first interrogation 38can be answered with “yes”, it is checked, in a second step 40, if thepresent speed of the electric motor 12 and thus of the drive shaft 14 islow. Thereby, a “low” speed means that the present speed is lower than aspeed which is present with “normal” conditions. Values which representthe speed of several kinds of tyres with “normal” conditions can beentered and recalled. A “low” speed indicates a torque which exceeds thecorresponding limit value. A “low” speed can be detected by the motorcurrent sensing device 24 in an increase of the current of the electricmotor 12. Alternatively, a “low” speed can be detected by a speed sensor(not shown) observing the speed of the drive shaft 14 or of the electricmotor 12. Corresponding signals are sent by the motor current sensingdevice 24 or the speed sensor to the converter 26, in particular to themicroprocessor 28 being part of the converter 26. For example, theactual low speed corresponds to the nominal speed of the motor at 50Hz—which approximately corresponds to 1500 rpm for a standard four-polemotor—and the actual high speed corresponds to the nominal speed of themotor at 100 Hz—which approximately corresponds to 3000 rpm for astandard four-pole motor. The actual low speed of the motor is reducedby means of a gearbox to about 7 rpm at the main shaft, and the actualhigh speed of the motor is reduced by means of a gearbox to about 14 rpmat the main shaft.

If the present speed of the electric motor 12 and thus of the driveshaft 14 is low, e.g. the second interrogation 40 is answered with“yes”, the present current of the electric motor 12 is compared with amaximum current in a third step 42. Thereby, it is checked, if thepresent current is greater than a maximum current. The present currentof the electric motor 12 is measured by the motor current sensing device24 and a corresponding signal is transmitted to the microprocessor 28.The microprocessor 28 compares the signal of the motor current sensingdevice 24, which corresponds to the measured current, with a storedlimit value for the present kind of tyre and detects if the presentcurrent of the electric motor 12 is greater than the maximum current.Limit values for several kinds of tyres are stored in the microprocessor28.

If the measured current of the electric motor 12 is greater than apreset limit, a time counter 37 starts (see step 44). If the measuredcurrent of the electric motor 12 persists for a preset time, e.g. forone second (see step 46), the “boost” function is started for about 0.2seconds. In other words, the “boost” function is conducted as long asthe interrogation “Count>1.2 s” can be answered with “no”, i.e. as longas the elapsed time is smaller than 1.2 seconds the “boost” function isconducted (see steps 48, 50). Is the elapsed time greater than 1.2seconds, the motor current is set back to normal condition (see step52). As already explained above, the “boost” function is synonymous withan activation of the pedal with which the electric motor 12 is started.That means the “boost” function simulates a pedal retry of an operatorwhich provides a torque peak of the electric motor 12. The frequencyand/or the amplitude of the motor current fed to the electric motor 12is changed, especially increased, within given limit values.

If there are detected any faults, the method is stopped (see steps 54,56). Otherwise, the method starts again (see steps 54, 58).

Furthermore, the motor is driven with normal condition (see step 52), ifthe present speed of the electric motor 12 and thus of the drive shaft14 is not low (i.d. interrogation 40 is answered with “no”), if thepresent current is lower than a maximum current (i.d. interrogation 42is answered with “no”) and if the measured current is for less than isgreater than the maximum current (i.d. interrogation 46 is answered with“no”).

Furthermore, if the pedal is not activated (see step 38), the method isstopped (see step 56).

Accordingly, it is autonomously detected, when the speed of the electricmotor 12 and thus of the drive shaft is slowed down due to high requestof torque, and the “boost” function is automatically started. Thereby,the frequency and/or the amplitude of the current fed to the electricmotor 12 is increased within maximum limits. This “boost” functionsimulates a pedal retry of an operator and provides a torque peak of theelectric motor 12.

For executing the inventive method for mounting/demounting a tyre to orfrom a rim, exemplarily for demounting a tyre from a rim, the operatormounts a vehicle wheel, which is a tyre/rim combination, to themounting/demounting apparatus.

Dependent on the kind of the tyre, the rim or the target to be achieved,like a high speed of the demounting process, or low noise emissionduring the process, the operator selects an operation mode by calling arespective program in control device 26 before starting themounting/demounting apparatus. Alternatively, a “standard” program maybe used to start the mounting/demounting apparatus, and after themounting/demounting apparatus has been started, the desired operationmode may be selected.

Naturally, in the case that the pedal is designed to start themounting/demounting apparatus, the operator may start the demountingprocess by pushing the pedal for starting and selecting a desiredoperation mode.

During the demounting process, sensing device 24 which is connected withcontrol device 26, transmits signals to the control device 26, forchecking the current consumption of electric motor 12. Then, as thedegree of electric current consumption can be related to the motorresistance torque, the frequency and/or the amplitude and/or the voltagecan constantly and automatically be adjusted to impart to the motor anoptimal torque/speed combination in view of the mounting/demountingconditions.

The mounting/demounting conditions are affected by the tire rigidity,especially by the rigidity of the tire beads, and by the kind of tireservicing operation that is being carried out.

In an exemplary case, the mounting/demounting apparatus can be startedwith the motor running at a “standard” speed. Then, by pressing e.g. apedal, the motor could be set to “automatic mode”, when the combinationspeed/torque is continuously automatically adjusted depending on actualconditions, as explained above. The motor speed could range from ca. 900rpm (corresponding to 20 Hz frequency, in the case of a four-polestandard induction motor), to ca. 4500 rpm (corresponding to 150 Hz);these speeds are then further reduced by means of a gearbox to a rangeof approx. 2.8 rpm to approx. 21 rpm. The initial “standard” speed couldbe set anywhere within that range. Thereby, speed ranges are broaderthan those of known mounting/demounting apparatuses.

It has to be noted that the mounting/demounting operation may be startedat a “standard” speed or according to a “standard” method, and thatafter being started, an alternative operation mode may be selected.Alternatively or additionally, according to the method of the presentinvention, the mounting/demounting operation may also be started with aselected specific operation mode as disclosed above.

It has further to be noted that an operation mode not necessarily needsto be executed at a single or constant torque/speed combination.Depending on the kind of the tyre to be treated and/or the target to beachieved, the torque/speed combination may be varied during themounting/demounting operation.

It has also to be understood that the operation mode may be changedduring the mounting/demounting operation, e.g. in the case that themounting/demounting conditions or in the case that the target to beachieved have been changed.

1. A method for mounting a tyre on a rim or demounting the tyre from therim, comprising: rotating a wheel, including an assembly of the tyre andthe rim, by an electric motor about an axis, selecting, depending on atarget to be achieved during a mounting or demounting operation, a setof plural operation modes of the electric motor from a plurality of setsof plural operation modes of the electric motor for the target to beachieved, each operation mode corresponding to a specific combination oftorque and speed of the electric motor, wherein when operating accordingto the selected set of operation modes, a first combination of torqueand speed of the electric motor is used during a first time period ofthe mounting or demounting operation, and a second combination of torqueand speed of the electric motor is used during a second time period ofthe mounting or demounting operation, the method further comprising:determining a current consumption of the electric motor during themounting or demounting operation, and continuously and automaticallyadjusting the first and second combinations of torque and speed of theelectric motor during the mounting or demounting operation based atleast in part on the determined current consumption.
 2. The methodaccording to claim 1, wherein the target is selected from the groupconsisting of maximizing a speed level of the electric motor, minimizingan electric energy consumption of the electric motor, minimizing noiseemission of the electric motor, and minimizing the speed level of theelectric motor.
 3. The method according to claim 1, further comprising:selecting the first and second combinations of torque and speed of theelectric motor by adjusting a frequency and/or an amplitude of a motorcurrent and/or a voltage.
 4. The method according to claim 3, furthercomprising: providing predetermined values of the frequency and/or theamplitude of the motor current and/or the motor voltage, whichcorrespond to the first and second combinations of torque and speed ofthe electric motor.
 5. The method according to claim 1, wherein thetarget of the selected set of operation modes is that the electric motorruns on a maximum speed level.
 6. The method according to claim 1,wherein the target of the selected set of operation modes is that theelectric motor runs on a minimum speed level.
 7. The method according toclaim 1, wherein the target of the selected set of operation modes isthat the electric energy consumption of the electric motor is minimized.8. The method according to claim 1, wherein the target of the selectedset of operation modes is that a noise emission of the electric motor isminimized.
 9. The method according to claim 4, wherein the target of theselected set of operation modes is that the electric motor runs on amaximum speed level.
 10. The method according to claim 4, wherein thetarget of the selected set of operation modes is that the electric motorruns on a minimum speed level.
 11. The method according to claim 4,wherein the target of the selected set of operation modes is that anelectric energy consumption of the electric motor is minimized.
 12. Themethod according to claim 4, wherein the target of the selected set ofoperation modes is that a noise emission of the electric motor isminimized.
 13. An apparatus for mounting a tyre on a rim or demounting atyre from the rim, comprising: an electric motor for rotating a wheel,including an assembly of the rim and the tyre, about an axis inaccordance with a set of plural operation modes of the electric motorselected from a plurality of sets of plural operation modes of theelectric motor depending on a target to be achieved during a mounting ordemounting operation, each operation mode corresponding to a specificcombination of torque and speed of the electric motor, a sensing devicefor sensing a motor current of the electric motor during the mounting ordemounting operation and transmitting corresponding signals to a controldevice, and a time counter connected to the control device, wherein whenoperating according to the selected set of operation modes, a firstcombination of torque and speed of the electric motor is used during afirst time period of the mounting or demounting operation, and a secondcombination of torque and speed of the electric motor is used during asecond time period of the mounting or demounting operation, the controldevice comprising an adjustment controller adapted to continuously andautomatically adjust the first and second combinations of torque andspeed of the electric motor during the mounting or demounting operationbased at least in part on the sensed motor current.
 14. The apparatusaccording to claim 13, wherein the adjustment controller is adapted toadjust a frequency and/or an amplitude of a motor current and/or avoltage of the electric motor.
 15. The apparatus according to claim 14,wherein the adjustment controller provides predetermined values of thefrequency and/or the amplitude of the motor current and/or the voltage.16. The apparatus according to claim 15, wherein, dependent on the firstand second combinations of torque and speed of the electric motor to beselected, one of the predetermined values of the frequency and/or theamplitude of the motor current and/or the voltage may be set.
 17. Theapparatus according to claim 13, further comprising a pedal forselecting the first and second combinations of torque and speed from aplurality of the combinations torque and speed.
 18. The method accordingto claim 1, wherein the electric motor runs at different selectablespeed levels for different kinds of tyres or different mounting ordemounting steps, and the continuously and automatically adjusting thefirst and second combinations of torque and speed of the electric motoris performed based at least in part on selections of kinds of tyres ormounting or demounting steps.
 19. The apparatus according to claim 13,wherein the electric motor runs at different selectable speed levels fordifferent kinds of tyres or different mounting or demounting modes, andthe apparatus further comprises a storage for storing the specificcombinations of torque and speed and an input for receiving selectionsof kinds of tyres or mounting or demounting modes.
 20. A method formounting a tyre on a rim or demounting the tyre from the rim using anelectric motor, comprising: selecting, depending on a target to beachieved during a mounting or demounting operation, a set of pluraloperation modes of the electric motor from a plurality of sets of pluraloperation modes of the electric motor for the target to be achieved,each operation mode corresponding to a specific combination of torqueand speed of the electric motor, wherein when operating according to theselected set of operation modes, a first combination of torque and speedof the electric motor is used during a first time period of the mountingor demounting operation, and a second combination of torque and speed ofthe electric motor is used during a second time period of the mountingor demounting operation, the method further comprising: rotating awheel, including an assembly of the tyre and the rim, by the electricmotor about an axis in accordance with the selected set of operationmodes, determining a speed of the electric motor during the mounting ordemounting operation, and continuously and automatically adjusting thefirst and second combinations of torque and speed of the electric motorduring the mounting or demounting operation, based at least in part onthe determined speed.